Method and apparatus for integrated wireless communications in private and public network environments

ABSTRACT

A communication system formed by a private network that includes a private wireless network. The communication system includes a public wireless network using a public wireless protocol, such as GSM, and includes public networks, such as PSTN, ISDN and the Internet, using a wired protocol, such as IP. The private network also includes a local area network (LAN) and the private network connects to the public networks using a wired packet protocol, such as IP. The public and private wireless networks operate with the same public wireless protocol, such as GSM, and the private wireless network additionally operates with a wired packet protocol, such as IP. The communication system permits users to operate freely in both public and private wireless networks using standard mobile stations while achieving high private network data rates. The communication system uses normal wireless handsets or other mobile or fixed stations without need for any modifications.

RELATED APPLICATION

This application is a continuation of U.S. application Ser. No.09/188,856, filed Nov. 9, 1998 now U.S. Pat. No. 6,539,237. The entireteachings of the foregoing application are incorporated herein byreference.

BACKGROUND OF THE INVENTION

The present invention is a method and apparatus that provides forwireless calls in private network environments and in public networkenvironments. More particularly, this invention relates to communicationsystems that interconnect wireless networks with private networks wherethe private networks typically are corporate networks that connect topublic networks such as PSTN, ISDN and the Internet.

Conventional Cellular Systems

Present day cellular mobile telephone systems provide for a large andincreasing demand for mobile services. Cellular systems “reuse”frequency within a group of cells to provide wireless two-way radiofrequency (RF) communication to large numbers of users. Each cell coversa small geographic area and collectively a group of adjacent cellscovers a larger geographic region. Each cell has a fraction of the totalamount of RF spectrum available to support cellular users. Cells are ofdifferent sizes (for example, macro-cell or micro-cell) and aregenerally fixed in capacity. The actual shapes and sizes of cells arecomplex functions of the terrain, the man-made environment, the qualityof communication and the user capacity required. Cells are connected toeach other via land lines or microwave links and to the public-switchedtelephone network (PSTN) though telephone switches that are adapted formobile communication. The switches provide for the hand-off of usersfrom cell to cell and thus typically from frequency to frequency asmobile users move between cells

In conventional cellular systems, each cell has a base station with RFtransmitters and RF receivers co-sited for transmitting and receivingcommunications to and from cellular users in the cell. The base stationemploys forward RF frequency bands (carriers) to transmit forwardchannel communications to users and employs reverse RF carriers toreceive reverse channel communications from users in the cell.

The forward and reverse channel communications use separate frequencybands so that simultaneous transmissions in both directions arepossible. This operation is referred to as frequency division duplex(FDD) signaling. In time division duplex (TDD) signaling, the forwardand reverse channels take turns using the same frequency band.

The base station in addition to providing RF connectivity to users alsoprovides connectivity to a Mobile Services Switching Center (MSC). In atypical cellular system, one or more MSC will be used over the coveredregion. Each MSC can service a number of base stations and associatedcells in the cellular system and supports switching operations forrouting calls between other systems (such as the PSTN) and the cellularsystem or for routing calls within the cellular system.

Base stations are typically controlled from the MSC by means of a BaseStation Controller (BSC). The BSC assigns RF carriers to support calls,coordinates the handoff of mobile users between base stations, andmonitors and reports on the status of base stations. The number of basestations controlled by a single MSC depends upon the traffic at eachbase station, the cost of interconnection between the MSC and the basestations, the topology of the service area and other similar factors.

A handoff between base stations occurs, for example, when a mobile usertravels from a first cell to an adjacent second cell. Handoffs alsooccur to relieve the load on a base station that has exhausted itstraffic-carrying capacity or where poor quality communication isoccurring. The handoff is a communication transfer for a particular userfrom the base station for the first cell to the base station for thesecond cell. During the handoff in conventional cellular systems, theremay be a transfer period of time during which the forward and reversecommunications to the mobile user are severed with the base station forthe first cell and are not established with the second cell.

Conventional cellular implementations employ one of several techniquesto reuse RF bandwidth from cell to cell over the cellular domain. Thepower received from a radio signal diminishes as the distance betweentransmitter and receiver increases. Conventional frequency reusetechniques rely upon power fading to implement reuse plans. In afrequency division multiple access (FDMA) system, a communicationschannel consists of an assigned particular frequency and bandwidth(carrier) for continuous transmission. If a carrier is in use in a givencell, it can only be reused in cells sufficiently separated from thegiven cell so that the reuse site signals do not significantly interferewith the carrier in the given cell. The determination of how far awayreuse sites must be and of what constitutes significant interference areimplementation-specific details. The cellular Advanced Mobile PhoneSystem (AMPS) currently in use in the United States employs FDMAcommunications between base stations and mobile cellular telephones.

In time division multiple access (TDMA) systems, multiple channels aredefined using the same carrier. The separate channels each transmitdiscontinuously in bursts which are timed so as not to interfere withthe other channels on that carrier. Typically, TDMA implementations alsoemploy FDMA techniques. Carriers are reused from cell to cell in an FDMAscheme, and on each carrier, several channels are defined using TDMAmethods. The Global System for Mobile Communications (GSM) and PCS 1900standards are examples of TDMA methods in current use.

The present specification uses a GSM system for purposes of explanationbut the present invention applies to any wireless system protocol.

GSM Cellular Systems

The GSM system architecture is described, for example, in detail by M.Mouly and M.-B. Pautet, The GSM System for Mobile Communications, 1992and Mouly and M.-B. Pautet, GSM Protocol Architecture: Radio Sub-systemSignaling, IEEE 41 st Vehicular Technology Conference, 1991. Thefollowing sections highlight some unique aspects of GSM systems.

The development of GSM started in 1982, when the Conference of EuropeanPosts and Telegraphs (CEPT) formed a study group called Groupe SpecialMobile. The main purpose of this group was to provide a single DigitalCellular standard in the 900 MHz band that could be used to unify thedisparate analog standards across Europe. In 1989, the responsibilityfor GSM was transferred to the European Telecommunication StandardsInstitute (ETSI), and the Phase I GSM recommendations were published in1990. At that time, the United Kingdom requested a specification basedon GSM but for higher user densities with low-power mobile stations, andoperating at 1.8 GHz. The specifications for this system, called DigitalCellular System (DCS 1800) were published 1991. Commercial operation ofGSM networks started in mid-1991 in European countries.

The GSM system specifications incorporate many advanced services andfeatures including:

ISDN compatibility based upon Q.931

World-wide roaming with other GSM networks

Two way messaging

Data Services

FAX Services

ISDN Supplementary Services.

However, the GSM system is designed fundamentally for use in atraditional Circuit Switched environment that uses 64 kbps voice anddata transport.

GSM System Architecture

The standard GSM network includes three major components, namely, theMobile Station (MS), Base Station Sub-System(BSS) and the NetworkSub-System(NSS). The GSM Specifications define the network entities andtheir associated interfaces within the Public Land Mobile Network(PLMN). The complete suite of specifications also includes documentsthat define the type approval procedures for mobile stations allowingmobile stations to be used in different countries, independently of thecountry in which they were type approved.

Base Station Subsystem (BSS)

The Base Station Subsystem (BSS) is composed of two main parts, the BaseTransceiver Station (BTS) and the Base Station Controller (BSC). The BTSincludes the radio transceivers that define the radio cell boundary andhandles the radio (Um) interface protocols with the mobile station.There are a number of different cell types, macro, micro and pico, thatcan be deployed dependent on the terrain, subscriber density andcoverage requirements. The macro cell is intended for large cell sizeswith ranges from 2 km to 70 km. The micro cell is intended to providecell sizes from 100 m to 5 km, either as an in fill or in areas servinga high density of subscribers. The pico cells are intended to supportcell sizes in the range 50 m to 1 km and will be used to provide highquality local radio coverage. The BTS supports all the required channelcoding, encryption and speech coding required by the radio interface.The speech transcoding may be performed- locally at the BTS or remotelyat the BSC or MSC. If remote transcoding is used, then the BTS is stillrequired to control this function.

The Base Station Controller (BSC) manages the radio resources of one ormore BTSs across the Abis interface. The BSC controls most of thefeatures of the radio network, including allocation of radio time slotsto a mobile station, release of the resources, interpretation ofmeasurement results and control of radio interface handovers. The BSCinterfaces to the NSS via the A-interface to the MSC.

Radio Transmission

The BTS is responsible for maintaining the radio link with the GSMMobile station. Currently the GSM system can support three frequencybands at 900, 1800 and 1900 MHz. However in each band the physical TDMAstructure is identical. Each RF carrier is divided into eight time slotsusing TDMA. Groups of eight consecutive time slots form TDMA frames.

There are two types of logical channels that are sent over the physicalradio interface and these are Traffic channels and Common ControlChannels. The traffic channels provide a bi-directional point-to-pointtransmission link to a mobile station. Full-rate Traffic Channels(TCH/F) and half-rate Traffic Channels (TCH/H) are allocated togetherwith a low bit-rate Slow Associated Control Channel (SACCH), whichtypically transmits measurements needed for handover decisions. Thereare also eighth-rate Traffic Channels, also called Stand-alone DedicatedControl Channels (SDCCH), which are used primarily for transmittinglocation updating information. In addition, a TCH slot can be pre-emptedfor signaling, in which case it is called a Fast Associated ControlChannel (FACCH), which can be either full-rate or half-rate TCHs.

Common channels can be accessed both by idle mode mobiles, in order tochange to dedicated mode, and by dedicated mode mobiles, to monitorsurrounding base stations for handover information. The common channels,which are defined include:

Broadcast Control Channel (BCCH)

Continually broadcasts, on the downlink, information including basestation identity, frequency allocations, and frequency-hoppingsequences.

Frequency Correction Channel (FCCH) and Synchronization Channel (SCH)

Used to synchronize the mobile to the time slot structure of a cell bydefining the beginning of a TDMA frame.

Random Access Channel (RACH)

Slotted Aloha channel used by the mobile to request access to thenetwork.

Paging Channel (PCH)

Used to alert the mobile station of incoming call.

Access Grant Channel (AGCH)

Used to allocate an SDCCH to a mobile for signaling in order to obtain adedicated channel), following a request on the RACH.

Speech and Channel Coding on the Radio Interface

Speech in GSM is digitally coded at a rate of 13 kbps, so-calledfull-rate speech coding. This rate is efficient compared with thestandard ISDN rate of 64 kbps. In addition, GSM also supports ahalf-rate speech code operating at around 7 kbps, effectively doublingthe capacity of a network.

This 13 kbps digital stream is split into (260 bits every 20 ms). Thisdata contains some forward error correction raising the gross bit rateafter channel coding to 22.8 kbps (or 456 bits every 20 ms). These 456bits are divided into eight 57-bit blocks, and the result is interleavedamongst eight successive time slot bursts for protection against bursttransmission errors.

Each time slot burst is 156.25 bits and contains two 57-bit blocks, anda 26-bit training sequence used for equalization. A burst is transmittedin 0.577 ms for a total bit rate of 270.8 kbps, and is modulated usingGaussian Minimum Shift Keying (GMSK) onto a 200 kHz carrier frequency.The 26-bit training sequence (TSC) is of a known pattern that iscompared with the received pattern to perform a channel estimation. Thischannel estimation is then used to recover the received signal. Forwarderror control and equalization contribute to the robustness of GSM radiosignals against interference and multipath fading.

Network Subsystem

An essential component of the Network Subsystem is the Mobile servicesSwitching Center (MSC). The MSC provides the functions required toswitch calls to/from the mobile user and the PSTN or ISDN fixed network.In addition the MSC also provides the functions needed to track andmaintain communication with a mobile subscriber, these includeregistration, authentication, location updating, inter-MSC handovers,and call routing to a roaming subscriber. In order to adequatelymaintain contact with the network subscribers the GSM PLMN employs anumber of databases. The main database functions are provided by twoLocation Registers, known as the Home Location Register (HLR) andVisitor Locations Register (VLR).

The Home Location Register (HLR) contains all the information related toan operators subscriber database. The HLR is the main database for anetwork. The HLR stores both static and dynamic data related to thesubscriber. Static data includes items such as International MobileSubscriber Identity, subscriber MSISDN number and registeredsupplementary services. Dynamic data includes, for example, currentlocation of the mobile user, in terms of VLR and MSC E.164 Number, andcall forwarding numbers. The HLR downloads the required data to a VLRdatabase when a Mobile User registers in a VLR area, it also providesthe necessary functionality to terminate mobile calls.

The Visitor Location Register (VLR) stores the subscribers data,downloaded from the HLR, for mobile stations currently located in theVLRs area. The data stored in the VLR may include information from theHome HLR and foreign HLRs. The VLR is used to provide both MobileOriginated and Mobile Terminated call functionality. The VLR is definedas an independent database in GSM, however in order to optimize systemperformance many implementations combine MSC and VLR functionality, thiseffectively makes the MSC and VLR areas identical.

The remaining two databases are associated with security aspects of thenetwork. The Authentication Center (AUC) is a secure database used toprovide authentication keys, based upon a secret key (ki), to the HLRand subsequently the VLR for verifying the validity of the userssubscription. The algorithm (A3) used to perform the authentication ofthe subscriber is stored in the users Subscriber Identity Module cardand Authentication Center (AUC), only the challenge and result are senton the radio interface. The challenge is also used by another algorithm(A8) to generate the key required by the A5 radio interface encryptionalgorithm. Although GSM defines possible A3 & A8 algorithms they aremore realistically defined by the operator. The remaining database isthe Equipment Identity Register (EIR) which contains a list of validinternational Mobile Equipment Identity (IMEI) values. The database cantherefore be used to control the use of stolen, non-type approved orfaulty mobile equipment. When a mobile subscriber registers with thenetwork the IMEI can be obtained and validated against the EIR data. Ifthe IMEI is blacklisted, then action can be taken to prevent networkaccess by the user.

Operations and Maintenance

Associated with the BSS and NSS equipment are Operations and MaintenanceCenter, OMC-R and OMC-S, respectively. The OMC-R provides the operationsand maintenance control of the GSM BSS functions. The OMC-R is used toperform the following functions:

Configuration of the Cells, this includes allocation of radio frequency,handover parameters, cell parameters and timer values.

Performance monitoring. This function allows the OMC-R to receivestatistical information about the various aspects of the BSS, such asnumber of calls, numbers of handovers etc.

Alarm reporting. The OMC-R is used to view and handle various alarmsthat are originated by the BSS. These may include hardware or softwarefailures, loss of connections, etc

Software Download. The OMC-R is responsible for providing and updatingthe software load to the BSS.

The NSS equipment is associated with the OMC-S. The OMC-S provides thesame type of high level functions as the OMC-R. In addition the OMC-Smay be used to provide user data administration for the HLR and VLR.However this function is more usually provided by a dedicatedAdministration Center which can also deal with Billing Serverrequirements and SIM data.

Services Provided by GSM

GSM was designed with ISDN interoperability as a pre-requisite,consequently the services provided by GSM are a subset of standard ISDNservices, however this is rapidly eroding as more ISDN services aredeveloped within the GSM fora. The GSM system provides a range of Basicand Supplementary Services. The Basic Services are further sub-dividedinto Teleservices and Bearer Services.

The Teleservices include:

Speech, the most basic service

Short Message, a two way messaging service

Group 3 FAX, this services allows connection to Group 3 FAX machines

Cell Broadcast, this service allows messages to be broadcast to themobile stations.

The Bearer Services include:

Asynchronous Data 300-14400 bps, allows access to normal V-Series Modems

Synchronous Data 300-14400 bps, allows access to CSPDNs

PAD Services

Packet Services

The Supplementary Services are intended to enhance the functionality ofthe Basic Services. The Phase 1 specifications only provide CallForwarding and Call Barring Services. The Phase 2 Supplementary servicesincluded Line identification services, advice of charge, multi-party,call waiting and call hold. The Phase 2+ services will include CallTransfer, Call Completion Busy Subscriber (CCBS) and Optimal routingcapabilities independent as possible from the underlying specifics ofthe mobile network. Another sublayer is Supplementary Services, whichmanages the implementation of the various supplementary services, andalso allows users to access and modify their service subscription. Thefinal sublayer is the Short Message Service layer, which handles therouting and delivery of short messages, both from and to the mobilesubscriber.

Problems with the Existing GSM Architecture

The current GSM cellular system is designed for large telephone companyinstallations, and is not cost-effective for installation of less thanapproximately 60,000 subscribers. Since the corporate market frequentlyhas a need for fewer than 60,000 users, the current GSM cellular systemdoes not adequately satisfy the market.

The standard cellular system uses expensive and large switchingplatforms that are limited to 64 kbps switching for voice or datatraffic. In the networks currently installed by many operatorsworld-wide, this 64 kbps fundamental limit prevents the cellularcustomer from receiving more advanced services such as video or highquality voice.

The current cellular systems use forms of Signaling System No 7 (SS#7)in order to establish the calls between mobile stations. Using thissignaling system again prevents the user from attaining the maximumpossible performance from the cellular network.

As wireless technology becomes more popular, corporations and otherentities having private networks desire to make their workers mobilewith the ability to access all voice and data information via wirelessdevices. Corporations might wish to integrate voice and data on aprivate Local Area Network (LAN). However using the current cellularsystems it is not possible to cost-effectively integrate wirelesssystems with private networks.

In the case of multiple corporate sites that need to be networkedtogether, there needs to be a method for communicating the location andidentity of users. Normally this information must be handled by large,dedicated central office switches (MSC). However, it would be moreoptimal to allow wireless terminals to communicate directly withoutdirect intervention by large telephone company equipment.

However, using current wireless technology, cellular phones areincompatible with private networks such as the corporate LAN which arebased on the Internet Protocol (IP).

In accordance with the above background, it is an object of the presentinvention to provide wireless systems that are compatible withconventional cellular systems and with corporate networks includinglocal area networks and the Intranet.

SUMMARY OF THE INVENTION

The present invention is a communication system formed by a privatenetwork that includes a private wireless network. The communicationsystem also typically includes a public wireless network using a publicwireless protocol, such as GSM, and typically includes public networks,such as PSTN, ISDN and the Internet, using a wired protocol, such as IP.The private network also typically includes a local area network (LAN)and the private network typically connects to the public networks usinga wired packet protocol, such as IP.

In the present invention, the public and private wireless networksoperate with the same public wireless protocol, such as GSM, and theprivate wireless network additionally operates with a wired packetprotocol, such as IP.

The private wireless network uses private base stations (P-BTS) whichinclude software for a wireless protocol, such as GSM, and includesoftware for private network operation with a wired protocol, such asIP.

The communication system permits users to operate freely in both publicand private wireless networks using standard mobile stations whileachieving high private network data rates. The communication systemtypically uses normal wireless handsets or other mobile or fixedstations without need for any modifications.

The private base stations (P-BTS) in one embodiment are directlyconnected to a private LAN and thereby enable standard wireless stationsto make and receive calls over the LAN. Also, the range of calls, usingstandard Internet protocols, extends between LANs and between differentcorporations over the Internet without requiring the support of a switch(e.g. MSC). The wireless stations can freely roam between the publicwireless network and the private wireless network and a single telephonenumber can be assigned to a mobile station for use in both the publicand the private wireless networks.

The foregoing and other objects, features and advantages of theinvention will be apparent from the following detailed description inconjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram representation of a communication systemincluding a public wireless network, other public networks such as PSTN,ISDN and the Internet and including a private network.

FIG. 2 depicts further details of the private network of FIG. 1.

FIG. 3 depicts a GSM BTS architecture with added private networksoftware.

FIG. 4 depicts a LAN interconnection of private wireless base stations(P-BTSs).

FIG. 5 depicts primary interface protocol stacks for IP-based privatewireless base stations (P-BTS).

FIG. 6 depicts a call processing plane of software modules for IP-Basedprivate wireless base stations (P-BTS).

FIG. 7 depicts an IP-based private wireless base station (P-BTS) gatekeeper plane of software modules.

FIG. 8 depicts IP-Based private wireless P-BTS OAM Software Modules.

FIG. 9 depicts a Location Registration Procedure.

FIG. 10 depicts the first phase of processing a mobile originated call.

FIG. 11 depicts the second phase of processing a mobile originated call.

FIG. 12 depicts the first phase of processing a mobile terminated call.

FIG. 13 depicts the second phase of processing a mobile terminated call.

FIG. 14 depicts a handover operation using wireless P-BTS.

FIG. 15 depicts an Virtual Private Network (VPN) interconnection to GSMPublic Land Mobile Network.

DETAILED DESCRIPTION

Communication System—FIG. 1

In FIG. 1, the communication system 10 includes a conventional publicwireless network 15, conventional public networks 8 (such as PSTN, ISDNand the Internet) and a private network 14. The public wireless network15 includes the ability to communicate in a conventional manner withconventional wireless mobile stations 4. The private network 14 includesthe ability to communicate with the conventional mobile stations 4 andprovides additional private network capabilities not provided by theconventional public wireless network 15.

The conventional public wireless network 15 of FIG. 1 includes themobile stations (MS) 4, Base Station Sub-System (BSS) 5 and the NetworkSub-System (NSS) 6. The Base Station Subsystem (BSS) 5 is composed ofthe Base Transceiver Stations (BTSs) 12 and the Base Station Controller(BSC) 16. Each of the BTSs 12 includes a radio transceiver that definesthe radio boundary of a cell 11 and handles the radio (Um) interfaceprotocols with the mobile stations 4.

The cell 11, in the wireless public network 15, of FIG. 1 each existover a different area and together the cells 11 collectively exist overa larger area designated as a region 111. Each cell 11 in the region 111uses frequencies that are isolated from the frequencies of other cellsin the region. As mobile stations 4 travel from a present cell 11 to anext cell 11, a frequency handover occurs from the frequencies of thepresent cell 11 to the frequencies of the next cell 11.

The private networks 14 of FIG. 1 include cells 11′ (including forexample cells 11′-1 and 11′-2) that each include a private P-BTS 27 forcommunications with mobile stations 4 located within the privatenetworks 14. Also, any of the cells 11′ can be sectorized so thatdifferent areas of a cell 11′ are partitioned into different sectors.For example, cell 11′-2 has six sectors 11″.

The cells 11′ and or sectors 11″, are within the domain of the privatenetworks 14 of FIG. 1, and also they are particular ones of the cells 11of the public wireless network 15 of FIG. 1. In today's environment, theallocation of frequency spectrum in different regions is undergovernmental control and is allocated to different entities in differentregions of a country. The owner of the rights to particular frequenciesin a region including public network 15 and private network 14 controlsthe allocation of frequencies among public cells 11, private cells 11′and sectors 11″.

The Base Station Controller (BSC) 16 manages the radio resources of oneor more BTSs across an Abis interface. The BSC 16 controls the radionetwork, including allocation of radio time slots to mobile stations 4,release of resources, interpretation of measurement results and controlof radio interface handovers. The BSC 16 interfaces to the NSS 6 via anA-interface to MSC 17.

The Network Subsystem (NSS) 6 includes the Mobile services SwitchingCenter (MSC) 17 that provides the functions required to switch callsto/from the mobile stations 4 and the fixed public networks 8 (includingPSTN and ISDN). In addition, the MSC 17 also provides the functionsneeded to track and maintain communication with mobile stations 4 andthese include registration, authentication, location updating, inter-MSChandovers, and call routing to roaming mobile stations 4. The GSM systememploys a Home Location Register (HLR) 19 and a Visitor LocationRegister (VLR) 13, an Authentication Center (AUC) secure database 2 andan Equipment Identity Register (EIR) 3. The Operations and MaintenanceCenter includes the OMC-R 7 and the OMC-S 9.

Private Networks—FIG. 2

In FIG. 2, private networks 14 include private networks 14-1, . . . ,14-N. Private network 14-1 is typical and includes the private wirelessnetworks 22 (including private wireless networks 22-1, . . . , 22-W),local area networks (LANs) 24 (including LANs 24-1, . . . , 24-L), andconnection units 29 (including connection units 29-1, . . . , 29-I). Theprivate networks 14 can include wide area networks (WAN) and any othertype of network presently or hereafter available. The connection unit 29includes a hub 23 for interconnecting the private wireless networks 22and the LANs 24 and for connecting the private network 14-1 to thepublic networks 8. The hub 23 connects to the router 33 that directscalls among the public network facilities including the ISDN 28, . . . ,PSTN 26 and the Internet 24 and the private networks 14. The privatenetworks 14 use the same protocol as the Internet 25 and connectdirectly without need for a separate gateway. The connection unit 29includes gateways 42-1, 42-2 . . . , 42-G for connecting the ISDN 28,PBX 43, . . . , PSTN 26 which use different protocols than the privatenetworks 14.

In FIG. 2, the private wireless networks 22 include the wirelesscapabilities of the public wireless network 15 of FIG. 1. In addition,the private wireless network 15 operates with advanced technologies thatare not yet available publically. Current advanced technologies operatewith rates of 384 kb/s and are approaching rates of 2 Mb/s. In FIG. 1,wireless communications between the public BTSs 12 and mobile stations 4operate with a wireless protocol such as GSM. In FIG. 2, wirelesscommunications between the private P-BTSs 27 and mobile stations 4 forconvenience and comparability operate with the same wireless protocol(such as GSM) as used by the public BTSs 12 in the public wirelessnetwork 15.

In FIG. 2, the local area networks (LANs) 24 are private wired networksoperating with a wired packet protocol such as IP. LAN 24-1 is typicaland includes, for example, a server 25 and LAN terminals 21 (includingterminals 21-1, . . . , 21-T). Terminals 21-1, . . . , 21-T communicatewith each other and with the public networks 8 through connection unit29 using the wired packet protocol.

In FIG. 2, the P-BTSs 27-1, . . . , 27-P are associated with protocolconverters 28-1, . . . , 28-P, respectively, that connect P-BTSs 27-1, .. . , 27-P to connection unit 23 using the private network protocol usedby the LANs 24 and the router 23. Therefore, the mobile stations 4communicating through the P-BTSs 27 in the private networks 14 haveaccess to the terminals 21 in LANs 24 and have access to the publicnetworks 8. Further, the P-BTSs 27 in the private wireless networks 14have available higher data rates than those available through the BTSs12 in the public wireless network 15. In the example described in thepresent specification, private rates up to 384 kbps are possible whereasconventional public cellular networks only provide rates up to 64 kbps.Accordingly, data retrieval operations in the private networks 14 arebetter accommodated than in the public wireless network 15 of FIG. 1.

In FIG. 2, the wireless P-BTS 27 directly connect the mobile stations 4through router 23 to other facilities in private networks 14 and therebypermit, for example, the mobile stations 4 to send and receive calls toand from the terminals 21 in the LAN networks 24. Furthermore, the rangeof calls from and to mobile stations 4 in the private wireless network22, using standard Internet protocols (IP), extends over the Internet inpublic networks 8 to any Internet facility such as different LANs anddifferent corporations in different regions or countries.

The private wireless networks 22 in FIG. 2 do not require the internalsupport of a circuit switch from the public networks and therefore, theprivate networks 14 in the FIG. 2 system can easily grow to accommodatenew user requirements under control of the owners of the privatenetworks 14.

In the private networks 14 of FIG. 2, the mobile stations 4 aretypically unmodified, conventional wireless mobile station handsets likethose widely used in conventional public wireless networks and thereforethe mobile stations 4 can freely move between the public wirelessnetwork 15 of FIG. 1 and the private wireless networks 22 of FIG. 2without restriction. Because of this free movement capability, only asingle number is required for each mobile station 4 for both privatewireless network communications and for public wireless networkcommunications.

The private wireless networks 22 of FIG. 2 have P-BTSs 27-1-1 27-P whichcorrespond, for example, to the cells 11′ and sectors 11″ of FIG. 1. Theallocation of frequencies among the public wireless network cells 11,the private network cells 11′ and the private network sectors 11″ isdetermined by agreement of the owners of the public wireless network 15and the private networks 14.

GSM BTS Architecture—FIG. 3

In a GSM example of the present invention, the FIG. 1 public wirelessnetwork 15 includes conventional GSM basestation software 31 asindicated in FIG. 3 including the components 31-1 and 31-2. The software31 and components 31-1 and 31-2 do not provide support for call controlor connection to the private wired protocol (Internet Protocol) that isused in the private networks 14 of FIG. 1 and FIG. 2. Accordingly, thesoftware 31 and components 31-1 and 31-2 require a protocol interface tofacilitate interoperation of the wireless protocol and the wired packetprotocol. For convinence, the protocol interfaces 28-1, . . . , 28-P arelocated with the P-BTSs 27-1, . . . , 27-P in the private wirelessnetworks 14 of FIG. 2 and are described in detail hereinafter.

P-BTS Architecture Overview—FIG. 4

The P-BTSs 27 are in the private wireless networks 14 of FIG. 1 and FIG.2 deployed, in one embodiment, as shown in FIG. 4. In this embodiment,each P-BTS 27 contains the required protocol stacks to perform thefunctions of the wireless control signaling from the mobile station 4and the H.323 Endpoint, gatekeeper 41 or gateway 42. In this embodiment,the H.323 Endpoint can be a PC based terminal 21 (see FIG. 2) or anothermobile station 4. The gatekeeper 41 provides the functions necessary tocontrol the “terminals” within the H.323 domain and, in this embodiment,“terminals” include GSM mobile stations 4.

The H.323 gatekeeper 41 provides the functions required to register themobile stations 4 (equivalent to Location Updating), permit access tothe network, translation of called numbers and routing of calls, ifrequired. These functions are largely equivalent to those normally foundin the MSC 17 or HLR 19 (see FIG. 1) of a public wireless network 15.The gatekeeper functions only need to exist in one P-BTS 27 of the P-BTS27-1, P-BTS 27-2 and P-BTS 27-3 within the H.323 zone of FIG. 4. In theFIG. 4 example, P-BTS 27-3 provides the gatekeeper function within theH.323 zone of FIG. 4 and supports the operation of P-BTS 27-2 and P-BTS27-1.

In order to support the full range of wireless functions, the functionsof a standard H.323 gatekeeper are augmented. The redesign includes theaddition of a Local User Database (LUDB) 6—6 (See FIG. 6) to control themobile station and provide Supplementary Services (SS) functionality.The gatekeeper database contents are transferred to the serving P-BTSwhen the mobile station 4 registers (that is, Location Updating hastaken place) on a P-BTS. For example, if a mobile station 4 hasregistered on P-BTS 27-1 in FIG. 4 and the user data of mobile station 4is stored with the gatekeeper 41 supported by P-BTS 27-3, then therelevant contents of the user database in P-BTS 27-3 are transferred toP-BTS 27-1 when the registration takes place. Any updates or alterationsto the data by interaction of mobile station 4 are reflected back to themain gatekeeper database 7-3 stored in the gatekeeper 41 (See FIG. 7).This approach reduces the amount of call control signalling that isrequired within a LAN and provides redundancy for increased reliability.

In order to provide external PSTN or public wireless networkinterconnection, an H.323 gateway 42 is provided in FIG. 4. The gateway42 is part of the normal VoIP LAN-P STN operation. The gateway 42provides line interface and transcoding functions that allow the voiceand data traffic to be sent to existing networks (for example, PSTN,ISDN, B-ISDN, PBX).

An additional function required of a P-BTS 27 when used in a LANenvironment of FIG. 4 is the ability to control the handover of mobilestations 4 between different P-BTSs 27 as mobile stations 4 move aroundwithin the LAN zone serviced by the private networks 14 of FIG. 4 andFIG. 2. The handover decision is made internally within each P-BTS 27,only the signaling necessary to command a handover needs to go betweenthe P-BTSs 27.

Protocol Stacks for Signaling—FIG. 5

To support the architecture, the standard GSM stack 31 of FIG. 3 ismodified by the P-Network Software 32 as shown in the FIG. 5. In FIG. 5,the components 31-1′ and 31-2′ are equivalent to the components 31-1 and31-2 in FIG. 3. As can be seen from FIG. 5, in addition to the privateWireless Air Interface requirements and the H.323 Terminal Equipmentrequirements, the LAN based P-BTS 27 also provides the followingfunctionality:

Interworking between the two Call Control Functions—private wireless andLAN based

Private Wireless Mobility Management (there is no BSC or MSC in stack 31of FIG. 3).

The Call Processing Plane Software Modules are significantly morecomplicated than those found in a normal public BTS and are defined inFIG. 6.

Call Processing Plane Software Modules for IP-Based P-BTS—FIG. 6.

In FIG. 6, the software modules for the call processing plane includemodules used for IP-based operation of P-BTSs 27 as follows:

Call Control Module—The module 6-1 is responsible for the “call featurecontrol” function for the mobile station, including both basic CallControl (CC) as well as Call Related Supplementary Services (CRSS).

The CRSS handled by this module include:

Calling Line Identification Presentation (CLIP)

Calling Line Identification Restriction (CLIR)

Connected Line Identification Presentation (COLP)

Connected Line Identification Restriction (COLR)

Call Forwarding Busy (CFB)

Call Forwarding No Reply (CFNR)

Call Forwarding Unconditional (CFU)

Call Waiting (CW)

Call Hold (HOLD)

Multi-Party Service (MPTY)

The Call Control Module is not merely an “interworking between theprivate Wireless Call Control and ISDN Call Control messages.” It isrequired to carry out the feature control functions, such as connectingvoice path, providing tones and announcements when call is not answered,working with Private gatekeeper entity in the local zone to obtainappropriate resource (e.g. conference circuit), forwarding a call, andmanaging call waiting and call hold features.

Tone and Announcement Module—The module 6-2 handles the actualgeneration of the various tone and announcement used according to theCall Control based on different call handling situation. Tone andAnnouncement are usually played towards the “far-end” this will be theLAN direction in this case, where only a tone is played toward the localMobile Direction.

Mobility Management Module—The module 6-3 is responsible for handlingthe Mobility Management Function of the mobile station, includinglocation update and handover control/co-ordination. This function wasoriginally located in the private wireless MSC and is fulfilled in theIP-based P-BTS. It also provides the ability to find a terminatingmobile station and the ability to handle the call when the mobilestation moves from one P-BTS to another P-BTS.

System Control Module—The module 6-4 is responsible for the End-Pointregistration, Administration, and status reporting in LAN. This entityis the “end-point” function and does not cover the gatekeeper functionswhich may be resident on the same P-BTS as well.

CISS Controller Module—The module 6-5 controls all the Call IndependentSupplementary Services (CISS) for the mobile station that is registeringthrough or served by the current P-BTS. The services include:

Subscriber activation/deactivation of various supplementary features,such as call waiting, call hold, call forwarding, etc.

Subscriber programming of the supplementary Service, such as theforwarded-to number when the mobile station is busy.

Most of the CISS features are of the interrogation type with thesubscriber setting information in the domain user database. This moduleis responsible for updating the local user database(LUDB), while theLUDB is responsible for ensuring the changes are carried back to thedomain user database (an HLR like database in the gatekeeper) correctly.

Local User Database Module (LUDB)—The module 6-6 maintains a copy ofuser data for each of the mobile stations that is registered on thecurrent P-BTS. The data is stored in local memory as a “cache.” Anychanges to the local copy will be “written-back” to the domain userdatabase automatically. All the other modules who need the user data tooperate interact with the Local User Database module for the datainterrogation. The Local User Database Module will interact with theDomain User Database Module when necessary and does it in a way that istransparent to all the other modules in the P-BTS.

RIL3-CC Encoder/Decoder Module—The module 6-7 is responsible forencoding and decoding the GSM Radio Interface Layer3 Call Controlmessages.

RIL3-MM Encoder/Decoder Module—The module 6-8 is responsible forencoding and decoding the GSM Radio Interface Layer3 Mobility Managementmessages.

H.225.0 RAS Encoder/Decoder Module—The module 6-9 is responsible forencoding and decoding the H.225.0 Registration Administration and Status(RAS) messages. This module is shared between Call Processing Plane andthe gatekeeper Plane.

H.225.0 CC Encoder/Decoder Module—The module 6-10 is responsible forencoding and decoding the H.225.0 Call Control messages. The H.225.0Call Control Message is based on ISDN Q.931 Message Set.

H.245 Encoder/Decoder Module—The module 6-11 is responsible for encodingand decoding the H.245 messages. The H.245 specification defines a setof messages for controlling the allocation and management of the logicalchannels for multimedia applications.

RRM Module—The module 6-12 is responsible for the entire Radio ResourceManagement functionality that is normally split between the BTS and theBSC in the traditional architecture. The RRM Module will directlyinterface with the Call Control Module for radio resource functions,such as channel set-up, paging, etc.

RIL3 Message Delivery Module—The module 6-13 is responsible for lookinginto the protocol discriminator field in the layer-3 message header todetermine which module has to process this message. The delivery of theCC message will now be sent to the RIL3-CC Encoder/Decoder Module, andthe MM message to the RIL3-MM Encoder/Decoder Module.

SMS-PP Controller Module—The module 6-14 is responsible in handling thePoint-to-Point SMS messages that are to be delivered to the targetmobile station.

SMS-CB Controller Module—The SMS-CB module 6-15 is used to keep track ofthe functionality of receiving and distributing the SMS CB messages thatare to be broadcast by all or part of the P-BTSs within the currentH.323 Zone.

Frequency Hopping Control Module—The module 6-16 controls the frequencyof communications for the target mobile station.

RIL3-RR Encoder/Decoder Module—The module 6-17 decodes and encodes theRIL3-RR messages to and from the BTS internal RR message formats. Theformats of the RIL3-RR messages are specified in the GSM TechnicalSpecification 04.08 along with the RIL3-MM, RIL3-CC, RIL3-SS, andRIL3-SMS messages specifications. This module provides the encoding anddecoding of the RIL3-RR message which is required for the P-BTS.

BTS Power Control Module—The module 6-18 is responsible for providingthe P-BTS power control (down-link) both statically and dynamically. TheP-BTS Power Control Module takes the Mobile Uplink Measurement Data thatis sent from a mobile, that is in dedicated mode, and compiled toprovide the best power adjustment strategy for the given mobile. Thegoal is to maintain the P-BTS power in the optimal level so that thesignal strength and signal quality for the down-link signal is withinthe private wireless quality guideline without causing excessiveinterference to the adjacent cell sites that are using the same oradjacent frequencies.

MS Power Control Module—The module 6-19 interfaces with the ChannelEncoding and Decoding to add/retrieve the power control informationinto/out-off the header fields of the Layer 1 messages. The retrieval ofthe Mobile's up-link power level and the encoding of the command toinstruct Mobile Station to increase/decrease the output power should beseparated from the intelligence of performing sliding window algorithmover Mobile's power level and making decision to increase or decreasethe MS power level.

BTS Measurement Report Module—The module 6-20 interfaces with GSM burstprocessing components to obtain the P-BTS measurement of the Mobileuplink signal. Specifically, the Automatic Gain Control and Demodulatorfor uplink power-level, and the Channel decoding unit for signalquality. Depending on the actual hardware architecture the input maycome from more than just the three components identified above.

Timing Advance Module—The module 6-21 interfaces with the Burst Formatfunction and retrieves the burst delay information for the Mobile, andthen interfaces with the Channel Encoding and Decoding to add the Mobiletiming advance information into the layer-1 header field. The TimingAdvance Module can be treated as part of the Traffic Channel ProcessingDomain or as part of the Call Processing Domain. It autonomouslymonitors the delay of the arriving burst and instructs the burstformatting function to encode the amount of timing-advance that themobile station needs to do in order to let the burst arrive within theburst envelope that the BTS is expected.

LAPDn Module—The module 6-22 interfaces the message delivery to thechannel coding/decoding.

IP-based P-BTS Gate Keeper Plane Software Modules—FIG. 7

In FIG. 7, the gatekeeper plane for gatekeeper 41 of FIG. 4 contains themodules which realize the wireless gatekeeper functionality as well as acombined Local/Domain User Database. Only one P-BTS 27 within each zonenormally will have this plane activated. It is also possible to have thegatekeeper 41 run in a dedicated mode without sharing the responsibilityof a P-BTS function. Therefore, logical separation is maintained betweenthe two entities even though they are expected to co-exist in the samehardware platform for many deployment scenarios. The IP-based P-BTS GateKeeper Plane Software Modules include:

Gatekeeper Module—The module 7-1 is responsible for the gatekeeperfunctionality as stated in the H.323 Specification. In one embodiment,the P-BTS may contain a gatekeeper entity along with an End-Pointentity. Even though the gatekeeper is almost always consulted by theCall Control and System Control entities in the end-point, the abovediagram does NOT show a direct connection among them. If all theentities are co-located in the same P-BTS, the traffic will actually goall the way to the IP layer, through the IP loop-back driver, and backto the correct entity.

Domain User Database Module—The module 7-2 maintains the Mobile User'sdatabase for the “Home Zone.” It is similar to the functionalityprovided by the GSM HLR, but without using GSM MAP for accessing thecontent of the database from the GSM MS C. The Domain User Database(DUDB) is responsible for communicating with the Local User DatabaseModule (LUDB) to provide a “cached copy” of the user data when themobile station performs a location update through the serving P-BTS. TheDomain User Database Module will be responsible for informing the LocalUser Database Module about the changes to the user data when thathappens. These include the delivery of Point-to-Point Short Messages tothe mobile station, the update from the network operator in changing thesubscription information of the mobile user, and Mobile User performsanother location update. Changes can be triggered in reverse directionfrom the Local User Database to the Domain User Database, such as MobileUser performs a Call Independent Supplementary Service to program itssupplementary services. In all cases, the Domain User Database Module inthe Gate Keeper only interacts with the User Local Database Module inthe P-BTS and not the various Call Control or CISS Modules directly.

Gate Keeper Database Module—The module 7-3 maintains the gatekeeper'sdatabase regarding all the mobile stations in the same zone as well asinformation regarding other gatekeepers in the connected network. SMS-PPController Module—The module 7-4 is responsible in handling thePoint-to-Point SMS messages that are to be delivered to the targetmobile station. The module 7-4 is the same as the module 6-14 in theCall Processing Plane of FIG. 6.

SMS-CB Controller Module—The SMS-CB module 7-5 is used to keep track ofthe functionality of receiving and distributing the SMS CB messages thatare to be broadcast by all or part of the P-BTSs within the currentH.323 Zone. The module 7-5 is the same as the module 6-15 in the CallProcessing Plane of FIG. 6.

H.225.0 RAS Encoder/Decoder Module—The module 7-6 is the same as themodule 6-9 as described in the Call Processing Plane of FIG. 6.

IP-Based P-BTS OAM Software Modules—FIG. 8

The OAM Software Modules for the IP-Based P-BTS uses an SNMP basedManagement Information Base (MIB). The new modules beyond those found ina normal public BTS are as follows:

SNMP Protocol Stack Module—The module 8-1 is the SNMP protocol stack asused to control the SNMP MIB.

SNMP Agent—The module 8-2 provides the agent side code to perform theaction request from the SNMP manager via the SNMP protocol.

SNMP MIB Controller Module—The module 8-3 is responsible for maintainingthe SNMP MIB (a logical view, from maintenance perspective, for all theresources) for the PBTS. The remote OAM commands from, for example anOMC-R are all carried out via changes to the MIB. The MIB controllerthan interprets the changes and performs the maintenance actions. Alarmand Performance reports from the P-BTS will also be collected and storedin the MIB. This module handles all the SNMP MIB, including additionalconfiguration and controlling attributes for the H.323 aspects of theP-BTS. Furthermore, the CC and MM functionality and RR functionality isalso managed by this module.

Initialization and Task Control Module—The module 8-4 is responsible forhandling the initialisation of all the other Software Modules,establishing communication, and monitoring the health of all theseprocesses through heart-beat (keep-alive timer) mechanisms.

Network Operations

This section describes several scenarios to demonstrate how anIntranet-based P-BTS 27 using the modules described above and deployedas shown in FIG. 4 provides the same type of services that are normallyprovided by a public cellular system that is based upon the conventionalGSM architecture. The following scenarios are representative of thoserequired for the support of cellular service and other scenarios can beconstructed from these building blocks.

Mobile Terminal Registration (Location Updating)

Private Terminal in Private Domain

Private Terminal in Public Domain

Public Terminal in Private Domain

Private Mobile Originated Call to:

Private Mobile or Fixed Terminal Located in Private Domain

Private Mobile or Fixed Terminal Located in Public Domain

Public Mobile Located in Private Domain

Public Mobile or Fixed Terminal Located in Public Domain Mobile

Terminated Call from:

Private Mobile or Fixed Terminal Located in Private Domain

Private Mobile or Fixed Terminal Located in Public Domain

Public Mobile Located in Private Domain

Public Mobile or Fixed Terminal Located in Public Domain

Handover within the LAN based P-BTS network.

It has been assumed in all the scenarios described below that the P-BTShandling the call has already performed the required registration phasewith its “local” wireless gatekeeper 41 entity(See FIG. 4). It shouldalso be noted that the P-BTS 27 handling the call may also be anotherP-BTS acting as the gatekeeper within the domain.

In the scenarios described below the following assumptions anddefinitions are used:

A Private Network in the cases described below is a network based uponthe P-BTS running with the modules described above. The user data forthe mobile stations is located in the private network gatekeeper 41 (SeeFIG. 4).

A Private Network Operator is considered to be the owner (for examplecorporation or other entity) of the private network including the P-BTSunits. It may be that the private wireless network is managed by thepublic network operator with guidance from the private network owner.

A Private Mobile is a wireless station that is serviced by the privatenetwork. The mobile station is also permitted to roam into the domainservice by the public wireless network depending upon agreements betweenthe operator of the public wireless network and the owner of the privatenetwork.

A Private Fixed Terminal is a terminal that is located on the LAN orattached PBX that is fixed in location. This may also be a normal fixedPBX phone or a phone attached to a desktop PC.

A Public Network is a normal public wireless network under the controlof a licensed operator. The network contains the usual cellular entitiessuch as MSC, VLR or HLR.

A Public Wireless Station is a wireless station that is primarilylocated on the cellular public wireless network. The mobile wirelessstation may also be permitted to roam into the private wireless domaindepending upon agreements between the operator of the public wirelessnetwork and the owner of the private network. The user data for thismobile user is located in the Public Network operators HLR.

A Public Network Operator is considered to be the licensed owner of apublic wireless network into which the domain of the private wirelessnetwork falls as related to the relevant spectrum.

In the cases described below, it is assumed that the mobile station 4 isa standard wireless station that need not have been modified. In such acase, the wireless station is a subscriber, having an Identity Module(SIM) card to identify the subscriber and contains a uniqueInternational Mobile Equipment Identity (IMEI).

In the descriptions below, it is assumed that the “network” is capableof performing number translations that allow calls to reach the privatenetwork gateway 42 (See FIG. 4) or the relevant public cellular network.This assumption implies that the wireless station number is uniquewithin the national numbering plan.

Mobile Terminal Registration

The registration operation needs to be performed for three differentscenarios:

Private Terminal in the Private LAN Zone.

Private Terminal in the Public Wireless Network.

Public Terminal in the Private LAN Zone.

Within each of these scenarios there are several variations that may beconsidered. In particular, one of the major items that will impact theoperation of the private network is the varying registrationrequirements that may be placed on the private mobile station 4. In eachof the sections below, the possible options are discussed in terms ofthe differences between the private network procedure and/or the normalpublic cellular network procedure.

Private Terminal Registration in the Private H.323 Zone

The terminal registration phase in the private LAN network is designedto appear identical to that found in a Public Wireless Network as far asthe Private mobile station is concerned. In order to accomplish thisoperation, the P-BTS is required to broadcast, on the Broadcast ControlChannel (BCCH), the same type of information as is found in a “normal”public wireless network 15. When the terminal detects and decodes thebroadcast channel information, it can then perform the usualregistration function as shown in FIG. 9. The registration function inthis case would be terminated at the wireless gatekeeper database. As analternative, the wireless gatekeeper can also contact a Public HLRdatabase to retrieve the User data for use by the P-BTS.

The signaling between the P-BTS and P-BTS/gatekeeper function uses thestandard H.323 Registration Request (RRQ) message sequence. If the RRQsequence fails, then a Location Reject messages is used to terminate theprocedure with the mobile station. The sequence shown in FIG. 9 is madeup of a number of phases as follows.

Phase 1: This phase is the normal Location Update request made by themobile station when it detects its Private (home) network. In this casethe Mobility Management (MM) layer in the P-BTS will terminate thesignaling for this message.

Phase 2: When the MM receives the Location Update request it mustinitiate a registration with the private wireless gatekeeper. In orderto perform this operation H.323/RAS signaling is used to send aRegistration Request (RRQ) to the private wireless gatekeeper. The RRQmessage will contain the IMSI of the registering mobile station, CallSignal, RAS and H.245 Transport Addresses for the P-BTS.

If the IMSI associated with the Private mobile station is alreadyregistered with this serving P-BTS then the registration, as an option,need not be checked with the gatekeeper. However in this case it wouldbe more usual to expect an “IMSI attach” rather than a Location Updaterequest.

If the TMSI security option is to be used within the Private domain thenon first registration it will be necessary to retrieve the IMSI if theLocation Area Identifier (LAI) is not recognized by the P-BTS receivingthe Locate Update request.

Phase 3: When the gatekeeper receives the RRQ it will check that theIMSI (or TMSI+LAI) presented in the RRQ is permitted to register on thePrivate Network. This function allows the Private Network Operator tocontrol access to the network. It is possible to enable or disableaccess to the network for Private or Public network users. Afterchecking the IMSI the private wireless gatekeeper may take severalactions dependent upon how the system has been configured.

If the IMSI belongs to a Private mobile station and the user data forthat mobile station is located in the gatekeeper database then thegatekeeper can return a Registration Confirmed (RCF) message to therequesting P-BTS. If the Private mobile station is already associatedwith another address (e.g. another P-BTS) then the gatekeeper canperform an Unregister Request (URQ/UCF/URJ) sequence to the old P-BTSaddress in order to eliminate duplicate information. It should be notedthat this operation sequence for the H.323 stack is unique to thisimplementation of the Invention.

If the IMSI belongs to a Private mobile station and the user data forthe mobile is not located in the gatekeeper then the gatekeeper requeststhe information for this user from another gatekeeper located elsewherewithin the Private network. This requires the transfer of data to thisgatekeeper before the processing can continue as described above.

If the IMSI belongs to a Public mobile station or to a Private mobilestation required to use the Public HLR then the gatekeeper requests therelevant database information from the Public Network HLR via a suitablymodified Private wireless gateway. The Private to Public gateway in thiscase takes the internal H.323 signaling and translate that into Privatewireless specific signaling for interworking with the Public NetworkHLR. In this case the data is relayed to the serving P-BTS. It alsopossible that the Public Network HLR will reject the request in whichcase the Location Update request from the Mobile User must also berejected. If the HLR accepts the request then it must store the E. 164number of the “gateway” in order to deal with Mobile Terminated Calls.

Phase 4: After the registration phase has been completed the data mustbe transferred from the Private wireless gatekeeper to the ServingP-BTS. In FIG. 9 this is shown by the TFTP message, however this is onlyused as an example other techniques could be used dependent upon theamount of data to be transferred. If small amounts of data are to bemoved then it could be added to the RCF message or an new message couldbe used based on the H.323 “Non Standard Message” option. The exactoption used does not affect the outcome required by this invention.

Phase 5: Once the data has been transferred to the serving P-BTS theregistration procedure can be completed to the mobile station.

Location Registration Procedure—FIG. 9

In FIG. 9, the private mobile station registration in Public GSM PLMN isdepicted. The exact method used to register the private mobile stationin the Public Network will depend upon the network configuration. Twooptions are described below where it is assumed that the private mobilestation is permitted to register in the Public Network.

Private Network Database: If the user data is held in a Private Networkdatabase on the Private wireless gatekeeper, as outlined above, thenwhen the Private mobile station registers in the Public Network theserving MSC will have to access this database via the gateway function.The Private wireless gatekeeper will retain the MSC and/or VLR Number inthis case for use with Mobile Terminating Calls.

Public Network Database: If the user data is held in the Public NetworkHLR, then the registration procedure is as per a normal GSM registrationprocedure.

Public mobile station Registration in the Private H.323 Zone: In thecase of the Public mobile station registering in the LAN zone, thePrivate wireless gatekeeper interrogates the Public Network HLR that isthe home location for the public mobile station.

Mobile Originated Call—FIG. 10 and FIG. 11

Four variations of the Mobile Originated Call (MOC) need to beconsidered and these are MOCs which is directed to:

Private Mobile or Fixed Terminal Located in Private Domain

Private Mobile in Public Domain

Public Mobile Located in Private Domain

Public Mobile or Fixed Terminal Located in Public Domain

The Mobile Originated Call (MOC) case is the most difficult in terms ofdetermining the destination of the call and how it is to be routed. Thesections below detail how this route determination is to be undertaken.

Mobile Originated Call to Private Mobile or Fixed Terminal Located inPrivate Domain

A Private Mobile User making a Mobile Originated Call would see the callprocedure as “identical” to the procedure found in a normal publicWireless Network, the call flow is illustrated in FIG. 10 and FIG. 11.The signalling between the P-BTS and Private wireless gatekeeperfunction would use the standard H.323 message sequences. The call flowsshown in FIG. 10 and FIG. 11 is made up of a number of phases:

Phase 1: This phase is the normal CM Service request made by the mobilestation when it wishes to make a Mobile Originated Call. In this casethe Mobility Management (MM) layer in the P-BTS will terminate thesignalling for this message.

Phase 2: The normal call establishment now continues with the mobilestation sending a SETUP message including the Called Party Number (CPN).The Connection Management (CM) layer is responsible for initiating thecall into the network.

Phase 3: The CM layer will begin the access process in the H.323 stackby using the RAS Admission Request (ARQ) sequence towards theP-BTS/gatekeeper. The purpose of this sequence is to both locate theterminating party and request LAN bandwidth for use in the call. In asmall or isolated network the ARQ sequence may be redundant, however itwould permit easy co-existence when the P-BTS resides in more heavilyloaded networks, it would also allow the gatekeeper to easily apply QoSprocedures to the P-BTS. The ARQ generated by the P-BTS will contain theCPN. The CPN number is used by the gatekeeper to determine the processto be followed in establishing the call. The exact process may beoperator specific and is not described in this invention.

The required routing information for the H.323/Q.931 SETUP message canbe returned to the serving P-BTS in the ACF message. If the informationcannot be resolved or other checks on the originating party fail thenthe call sequence may be rejected at this point and the call terminated.

Phase 4: Upon receipt of the ACF the serving P-BTS can now route theH.323 SETUP message to the destination. It should be noted that thedestination may apply call forwarding or other forwarding operations. Assoon as the H.323 Call Proceeding is received the CM layer can proceedwith the call processing towards the mobile station.

Phase 5: When the H.323 Call Proceeding message has been received by theH.323 stack establishment of the audio channel can begin. This isundertaken by the Terminal Capabilities, Master/Slave and Bi-DirectionalChannel Open (B-OpenChn) sequence. This will allow conversation as soonas the mobile station has been assigned to a radio Channel, therebyavoiding any speech clipping problems.

Phase 6: The completion of the call will begin with the sending of aCall Proceeding message to the mobile station. This can then be followedby an assignment of the mobile station to the traffic channel (TCH). TheAlerting and Connect sequence are then used to complete the callestablishment process.

In establishing this call it has been assumed that the terminating partyis either a Private mobile station or Private Fixed Terminal within thesame H.323 area. In this case, the Terminal Capabilities negotiationprocess takes care of selecting the correct code.

In FIG. 10 and FIG. 11, the operation of a Mobile Originated Call to aPrivate mobile station Located in Public Domain is represented. If theMobile Originated Call is to another Private mobile station which is nowregistered on the Public Domain, there are two possible optionsdepending upon how the user data is stored in the network. If the userlocation data is stored by the Private wireless gatekeeper, then theaddresses necessary to route the call will be returned in the ACF, whichshould point to the Public MSC/VLR serving the Private mobile station.If the user location data is stored in the Public Cellular network HLRthen the gatekeeper will either have to request the location data fromthe Public HLR or simply route the call directly to the gateway then tothe nearest MSC. Therefore the routing data for the call will beprovided directly by the HLR or indirectly via the MSC. In all of thesecases the H.323 SETUP message will be routed to the gateway entity forrouting to the external network. In this case it will also be necessaryto use the transcoding functions of the gateway entity.

Public Mobile Located in Private Domain

If the Mobile Originated Call is to Public Mobile which is nowregistered on the Private Domain there are two solutions depending uponhow the user data is stored in the network. If the Public user locationdata is stored by the Private wireless gatekeeper, this pointer is usedto “short circuit” the need to interrogate the Public HLR and theaddresses necessary to route the call is returned in the ACF, whichpoints to the P-BTS serving the Public mobile station. In this case, theH.323 SETUP message is routed directly to the P-BTS serving the Publicmobile station.

If the user location data is stored in the Public HLR, then the Privatewireless gatekeeper requests the location data from the Public HLR. Thisoperation provides the routing data for establishing the call via theH.323 gateway. In this case, the gateway is responsible for determiningthe location of the Public User. Therefore, in practice, the schemementioned in the previous paragraph is optimum in terms of signallingperformance since the gatekeeper only needs to interrogate the PublicHLR if the Public mobile-station cannot be found in the Private Network.

Public Mobile or Fixed Terminal Located in Public Domain

If the Mobile Originated Call is to a Public mobile station or FixedTerminal located in the Circuit Switched Telephone (CST) domain, thenthe routing of the call is directly to the gateway. However it may bethat in order to speed up the establishment of the call, the Privatewireless gatekeeper will search for the CPN on the Private Network firstbefore routing the call to the gateway. The gateway is then responsiblefor signalling and providing the necessary transcoding functions.

Mobile Terminated Call—FIG. 12 and FIG. 13

The Mobile Terminated Call needs to be performed for four differentscenarios:

Private Mobile or Fixed Terminal Located in Private Domain

Private Mobile or Fixed Terminal Located in Public Domain

Public Mobile Located in Private Domain

Public Mobile or Fixed Terminal Located in Public Domain

The Mobile Terminated Call (MTC) case is the most straightforward callscenario. In most of the above cases, the call flows are identical, theonly difference being the terminating point and the signalling requiredto reach that point.

Private Mobile or Fixed Terminal Located in Private Domain to PrivateMobile

This case covers two scenarios, calls from another fixed computerterminal using H.323 and calls from another Private mobile station. Inboth of these cases, the call flows are identical, once the destinationaddress of the Private mobile station has been determined. The callflows shown in FIG. 12 is made up of a number of phases:

Phase 1: The initial phase of a Mobile Terminated Call establishment isstarted by the arrival of the H.323 SETUP message from the calling partyon the well known Q.931 Signaling address in the P-BTS. The CPN numberin the SETUP message is then used to lookup up paging information forthe Private mobile station. The H.323 Call Proceeding message isreturned to the originating endpoint.

Phase 2: The normal Paging request is now made to the mobile stationwhen the Private Network wants to make a Mobile Terminated Call. Whenthe mobile responds to the Page Request the normal Authentication andCiphering procedures can be performed. During this time it should bepossible for the RAS layer to begin the ARQ sequence with the registeredgatekeeper in order to reserve the required bandwidth.

Phase 3: The GSM call establishment procedures now continue with themobile station receiving a SETUP message including the BearerCapabilities for the call being established, this is required to makesure the mobile station can correctly determine the type of call. Forexample, an MTC Data call may require a modem to be enabled in themobile station. When the Call Confirmed message is received from themobile station then the H.323 stack can then proceed with the LAN partof the call.

Phase 4: When the H.323 stack receives the Call Confirmed message fromthe mobile station the H.245 layer should begin the necessary TerminalCapabilities, Master/Slave and Bi-Directional Channel Open (B-OpenChn)sequence in order to establish the RTP/RTCP transport link between theendpoints.

Phase 5: In this phase the mobile station can now return the Alertingand Connect messages which are forwarded to the originating endpoint inthe Private Network. Upon receipt of the CONNECT message the CM layercan request the assignment of the required radio resources.

In establishing this call it has been assumed that the terminating partyis either a Private mobile station or Private Fixed Terminal within thesame H.323 area. In this case, the Terminal Capabilities negotiationprocess takes care of selecting the correct code.

The call release scenario is also given in FIG. 13.

Private Mobile or Fixed Terminal Located in Public Domain

In the case of a Fixed Terminal Circuit Switched Telephone (CST) call toa Private mobile station on the private network, the call is firstrouted to the nearest H.323 gateway by the PSTN/ISDN network (this maydepend on local regulations). The gateway will then be required tointerrogate its local Private wireless gatekeeper, which may have tointerrogate other gatekeepers, in order to find the required routinginformation. Once the routing information has been returned, then thecall can be established through the Intranet to the terminating P-BTS.

Public Mobile Located in Private Domain

In the case of a Public mobile station located in the Private Networkthe first requirement is to locate the destination address of the calledmobile. This would involve the serving P-BTS interrogating itsregistered Private wireless gatekeeper to determine the routing address.Once the routing address has been determined the call can be routed tothe terminating mobile.

Public Mobile or Fixed Terminal Located in Public Domain

In the case of a Fixed Terminal CST call to a Private mobile station onthe private network the call is first routed to the nearest H.323gateway by the PSTN/ISDN network (this may depend on local regulations).The gateway will then be required to interrogate its local Privatewireless gatekeeper, which may have to interrogate other Privatewireless gatekeepers, in order to find the required routing information.Once the routing information has been returned then the call can beestablished through the Intranet to the terminating P-BTS.

Handover Operation With P-BTS—FIG. 14

In FIG. 14 details of a handover operation are shown. The handoverscenarios fall into the following categories:

Intra-Private Network Handover.

Inter-Private Network Handover

Private to Public Network Handover

Public to Private Network Handover

The first two cases are dealt with in the next section as they are verysimilar. The last two cases are not described in detail since they canbe built from the first two.

Intra-Private Network Handover Inter-Private Network Handover

In order to provide continuous coverage within the private domain(Intranet), it is necessary to be able to perform at least intra-domainand inter-domain handovers. In order to simplify the implementation ofthe network, the P-BTS performs the handover candidate calculations onthe measurement data being sent by the mobile station. Once a handovercandidate has been identified and the decision made, then the process tobegin the handover needs to be started. There are several methods usedto facilitate the handover process. The simplest solution is to use theconference facilities of H.323 and the resources of thegatekeeper/Multi-Conference Unit (MCU) to bridge the old P-BTS and thetarget P-BTS. Another method uses the multicast options of the Intranetto send the uplink and downlink IP packets to both the old and newP-BTSs. In either case, the target P-BTS enables the new radiointerface, prepares to take over the mobile station Call Control statemachine and establishes the necessary routing to access the network.Once the new radio channel has been established, the terminal isinstructed to move to the new P-BTS and the old P-BTS resources arereleased. If each P-BTS used a different LAI, then location updating(registration) is automatically performed when the call terminates. Inperforming the handover as shown in FIG. 14, the following phases areundertaken:

Phase 1: Once the handover algorithm has determined that a handover isrequired then the transport addresses of the new base station must bedetermined. The new base station address is determined by making use ofthe RAS Location Request with the BTS ID as the addressed party. Whenappropriate this operation is extended to include the locations of BTSswithin the Public GSM network.

Phase 2: If the gatekeeper knows the transport addresses of the TargetBTS (EP3) then it is returned in the Location Confirm (LCF) message. Atthis point the Old BTS (EP 1) must request the resources from the TargetBTS. The resource request is performed by adding a new “Non-StandardMessage” to the H,323 repertoire. This new message requests theresources from the Target BTS. This message may also include callcontrol information appropriate to this mobile station. In addition, tospeed up the location updating process, it may also include the Old BTSscopy of the user data.

In the case of a handover to the Public network then the “Non-StandardMessage” would have to be sent to the gateway and converted into theappropriate Handover message for the public network. The gateway wouldalso have to start handling the call for the Old BTS.

Phase 3: When the Target BTS receives the request for the resources, ifthey are available then it will respond with a confirmation and amulticast address to be used by the Old BTS.

Phase 4: Upon receiving the confirmation the Old BTS begins to establisha conference between the destination BTS (EP2) or Fixed Terminal and theTarget BTS. Once the multicast distributed conference has beenestablished the Old BTS can instruct the mobile station to handover tothe Target BTS.

Phase 5: The Handover Command is sent to the mobile station which willthen begin to access the Target BTS on the indicated timeslot, Once themobile station is established on the Target BTS an End Session messageis sent to the Old BTS to release the resources from the BTS. The CallControl is now located on the Target BTS.

In order to accommodate different handover cases, the P-BTS determinesvia the BTS ID whether Synchronized or Non-synchronized handover is tobe used.

It should be noted that this procedure is equally applicable to bothPrivate and Public mobile stations. This procedure also forms the basisfor any scheme which requires handover to/from the Public GSM network.

VPN Interconnection To GSM PLMN—FIG. 15

In FIG. 15, a P-BTS Virtual Private Network (VPN) 34 formed by theP-BTSs 27-1, 27-2 and 27-3′ interconnects to GSM PLMN 26 through hub 23and router 33 to the Internet 24. In FIG. 15, the wireless gatekeeper41′ is part of the P-BTS 3 27-3′. The gatekeeper 41′ communicates withthe Public Cellular HLR 19 using a reduced form of the normal PublicWireless Cellular Signaling system. The HLR 19 can then be contactedusing the Internet over a dedicated trunk line from a gateway. The trunklines connect the H.323 gateway to the MSC and then to the HLR 19. Atthe HLR 19, an IP SS7 translator is used, to convert the incomingcontrol signalling riding on IP to be sent over SS7 and vice-versa. Inorder to efficiently support private/public roaming, the IP to SS7translation entity is best co-located with the Public Cellular NetworkHLR 19, where it can be used to service many private networks such asnetworks 14′-1, . . . , 14′-M as well as private network 14-1 in FIG.15. Using this scheme, Public-to-Private and Private-to-Public roamingis easily performed. The IP/SS7 translator is available from manymanufacturers. This function is also used to transport Short Messages toand from the Private/Public domain.

The support of handover is achieved with the addition of handoversupport in the gateway entity and an IP-to-SS7 convertor co-located withthe nearest MSC. This addition allows handover, messages to be passed toand from the MSC, via the H.323 gateway and then to the serving P-BTS.

While the invention has been particularly shown and described withreference to preferred embodiments thereof it will be understood bythose skilled in the art that various changes in form and details may bemade therein without departing from the scope of the invention. Someterms used in the specification are set forth in the following GLOSSARY.

GLOSSARY ALS Alternate Lines Selection ARS Automatic Route Selection CARCall Detail Record CC Call Control DHCP Dynamic Host ConfigurationProtocol DNS Domain Name Server GoIP GSM over IP GSM Global System forMobile Communications HTML Hyper Text Markup Language IMEI InternationalMobile Equipment Identity IMSI International Mobile Subscriber Identity(based on E.212 numbering) IrDA Infra red Digital Access ISDN IntegratedServices Digital Network Java Programming language from Sun MicroSystemsLAI Location Area Identifier LCR Least Cost Routing MIB ManagementInformation Base MM Mobility Management MS Mobile station MSIDN Mobilestation ISDN Number NNTP Network Time Protocol OAM Operations,Administration & Maintenance PDA Personal Digital Assistant PLMN PublicLand Mobile Network RR Radio Resource SMS - CB Short Message Service -Cell Broadcast SMS - PP Short Message Service - Point-to-Point SNMPSimple Network Management Protocol SNTP Simple Network Time ProtocolTMSI Temporary Mobile Subscriber Identity VPN Virtual Private Network

What is claimed is:
 1. A method for allowing a mobile station tocommunicate in a wireless communication system, the wirelesscommunication system comprising a plurality of private base transceiverstations, the private base transceiver stations having radiotransceivers that communicate data and signaling information with themobile station, the private base transceiver stations also having aprocessing layer for mobility management and a call control processinglayer contained within them, the private base transceiver stationsinterconnected by a packet data network, the method comprising the stepsof: receiving a call control message at the private base transceiverstations and passing the call control message to the processing layerfor mobility management resident within the private base transceiverstations, without forwarding the call control message to a base stationcontroller, the call control message including a control functionidentifier and a mobile station identifier; forwarding the call controlmessage internally within the private base transceiver stations to apacket interface layer in the private base transceiver stations, thepacket interface layer providing communication between the private basetransceiver stations and other nodes connected to the packet datanetwork; at the packet interface layer, formatting an external controlmessage intended for transmission over the packet data network, theformatted external control message indicating an alias identifiercorresponding to the mobile station identifier; and forwarding theformatted external control message across the packet data network.
 2. Amethod as in claim 1 in which the call control message requesting alocation update and received from the mobile station at the private basetransceiver stations and being passed to the processing layer formobility management resident within the private base transceiverstations additionally, comprises: reformatting the call control messageas an external message requesting registration by the packet interfacelayer, the external message specifying the mobile station identifier;sending the external message from the packet interface layer over thepacket data network; and receiving a confirmation message confirmingregistration over the packet data network, the confirmation messageincluding a packet data network identifier for the mobile station, thepacket data network operable for direct communication with a publicwireless network.
 3. A method as in claim 2 additionally comprising:before the step of sending the external message, issuing a channelrequest message from the mobile station to a layer for radio resourcefunctions resident within the private base transceiver stations; andreturning an immediate channel assignment message from the layer forradio resource functions to the mobile station.
 4. A method as in claim3 additionally comprising: returning a message confirming acknowledgmentfrom the packet data network indicating call parameters as anencapsulated packet data network message.
 5. A method as in claim 1additionally establishing a connection for a mobile station initiatedcall, comprising the steps of: sending a call setup message from themobile station to the private base transceiver stations, the call setupmessage being received at the processing layer for mobility management,the call setup message indicating a called party number; forming aninternal setup message in a layer for connection management associatedwith the private base transceiver stations, and forwarding the internalsetup message to the packet interface layer of the private basetransceiver stations; and forming a message requesting acknowledgmentfrom the internal setup message, and forwarding the message requestingacknowledgment across the packet data network.
 6. A method as in claim 5additionally comprising: sending a setup message from the private basetransceiver stations across the packet data network, the setup messageincluding an indicator of the called party number to be used by themobile station; in response thereto, receiving, at the private basetransceiver stations, a call proceeding message from the packet datanetwork; forwarding the call proceeding message internally to the layerfor connection management within the private base transceiver stations;and forwarding a call proceeding message from the layer for connectionmanagement through to the processing layer for mobility management, tothe mobile station.
 7. A method as in claim 1 additionally comprisingterminating a call at a mobile station, comprising the steps of:receiving, from the packet data network, a setup message encapsulated ina data network message; forwarding the setup message through an internalprotocol stack as an internal setup message indicating a called partynumber and other configuration information to the layer for connectionmanagement in the private base transceiver stations; and sending aninternal page request message from the layer for connection managementto the layer for radio resource functions within the private basetransceiver stations.
 8. A method as in claim 7 additionally comprising:the layer for radio resource functions issuing a paging request messageto the mobile station; and in response thereto, the mobile stationreturning a paging response message indicating a mobile stationidentifier to the processing layer for mobility management to initiate abegin call sequence.
 9. A method as in claim 8 additionally comprising:after the call setup message is received at the layer for connectionmanagement; providing a begin call internal message from the layer forconnection management to the packet interface layer, the begin callmessage initiating a message requesting acknowledgment that includes themobile station identifier and called party number; receiving, from thepacket data network, a message confirming acknowledgment indicatingconnection information; and generating an internal accepted call messageusing the received message confirming acknowledgment to establish theability to receive a call.
 10. A method as in claim 9 additionallycomprising: in response to receiving the accepted call message at thelayer for connection management, generating a setup message to themobile station, the setup message indicating a called party number andchannel number; returning a call confirmed message from the mobilestation to the layer for connection management; generating an internalcall confirmed message from the layer for connection management to thepacket layer interface; and generating an open channel message from thepacket layer interface to the packet data network to open channels forinformation transfer.
 11. A method as in claim 1 in which the callcontrol messages indicate a handover of servicing the mobile stationfrom a serving private base transceiver stations to a target privatebase transceiver stations, further comprising: passing a handoverrequest message from the layer for connection management within theprivate base transceiver stations to the packet layer interface;generating a location request message indicating the private basetransceiver stations identifier and called party number; and returningfrom the packet data network a location confirmation message indicatinghandover processing information.
 12. A method as in claim 11additionally comprising: forwarding a handover message from the packetlayer interface as a nonstandard packet data network message indicatinga handover request; and receiving a handover acceptance message as anonstandard packet data network message.
 13. A method as in claim 12additionally comprising: upon receipt of a connection message from thetarget private base transceiver stations reporting on allocation ofresources, bridging a release complete message received from the targetprivate base transceiver stations at the serving private basetransceiver stations from the packet layer interface to the layer forconnection management; bridging the release complete message from thelayer for connection management to the processing layer for mobilitymanagement; and forwarding a handover command from the processing layerfor mobility management to the mobile station.
 14. The method of claim 1wherein the external control messages causes a protocol address of theprivate base transceiver stations associated with the mobile stationidentified by the mobile station identifier to be changed to a differentprotocol address of a different private base transceiver stations.
 15. Acomputer program product having computer program code for allowing amobile station to communicate in a wireless communication system, thewireless communication system comprising a plurality of private basetransceiver stations, the private base transceiver stations having radiotransceivers that communicate data and signaling information with themobile station, the private base transceiver stations also having aprocessing layer for mobility management and a call control processinglayer contained within them, the private base transceiver stationsinterconnected by a packet data network, comprising: computer programcode for receiving a call control message at the private basetransceiver stations and passing the call control message to theprocessing layer for mobility management resident within the privatebase transceiver stations, without forwarding the call control messageto a base station controller, the call control message including acontrol function identifier and a mobile station identifier; computerprogram code for forwarding the call control message internally withinthe private base transceiver stations to a packet interface layer in theprivate base transceiver stations, the packet interface layer providingcommunication between the private base transceiver stations and othernodes connected to the packet data network; computer program code for,at the packet interface layer, formatting an external control messageintended for transmission over the packet data network, the formattedexternal control message indicating an alias identifier corresponding tothe mobile station identifier; and computer program code for forwardingthe external control message across the packet data network.
 16. Thecomputer program product of claim 15 wherein the external controlmessages causes a protocol address of the private base transceiverstations associated with the mobile station identified by the mobilestation identifier to be changed to a different protocol address of adifferent private base transceiver stations.
 17. A wirelesscommunication system including a plurality of private base transceiverstations, the private base transceiver stations having radiotransceivers that communicate data and signaling information with themobile station, the private base transceiver stations also having aprocessing layer for mobility management and a call control processinglayer contained within them, the private base transceiver stationsinterconnected by a packet data network, comprising: a private basetransceiver stations operable to receive a call control message at theprivate base transceiver stations and pass the call control message tothe processing layer for mobility management resident within the privatebase transceiver stations, without forwarding the call control messageto a base station controller, the call control message including acontrol function identifier and a mobile station identifier; a packetinterface layer in the private base transceiver stations operable toreceive the forwarded call control message internally within the privatebase transceiver stations, the packet interface layer further operableto provide communication between the private base transceiver stationsand other nodes connected to the packet data network; an externalcontrol message formatted at the packet interface layer and intended fortransmission over the packet data network, the formatted externalcontrol message indicating an alias identifier corresponding to themobile station identifier; and a packet data network operable to forwardthe external control message.
 18. The wireless communication system ofclaim 17 wherein the external control messages causes a protocol addressof the private base transceiver stations associated with the mobilestation identified by the mobile station identifier to be changed to adifferent protocol address of a different private base transceiverstations.
 19. A wireless communication system including a plurality ofprivate base transceiver stations, the private base transceiver stationshaving radio transceivers that communicate data and signalinginformation with the mobile station, the private base transceiverstations also having a processing layer for mobility management and acall control processing layer contained within them, the private basetransceiver stations interconnected by a packet data network,comprising: means for receiving a call control message at the privatebase transceiver stations and for passing the call control message tothe processing layer for mobility management resident within the privatebase transceiver stations, without forwarding the call control messageto a base station controller, the call control message including acontrol function identifier and a mobile station identifier; means forforwarding the call control message internally within the private basetransceiver stations to a packet interface layer in the private basetransceiver stations, the packet interface layer operable to providecommunication between the private base transceiver stations and othernodes connected to the packet data network; means for, at the packetinterface layer, formatting an external control message intended fortransmission over the packet data network, the formatted externalcontrol message indicating an alias identifier corresponding to themobile station identifier; and means for forwarding the external controlmessage across the packet data network.
 20. The wireless communicationsystem of claim 19 wherein the external control messages causes aprotocol address of the private base transceiver stations associatedwith the mobile station identified by the mobile station identifier tobe changed to a different protocol address of a different private basetransceiver stations.